In the field of single-site polymerization of olefins, typical catalyst compositions comprise organometallic catalysts such as metallocenes contacted with activating cocatalysts such as alumoxanes. The synthesis and isolation of metallocenes can be difficult due to their air and moisture sensitivity. Yields are often poor with more complex kinds of catalysts. Thus, catalyst cost can be substantial. Moreover, it is difficult to change substantially the rates and product properties of these catalysts once they have been made, since the ligand of the catalyst exerts overwhelming control over the catalyst composition properties. Thus, such catalysts are not especially amenable to processes using a variety of conditions or producing a variety of products.
Catalyst compositions that can be assembled at the site of the reactor are advantageous in terms of cost because isolation and purification is avoided. Moreover, catalysts previously considered non-isolable or catalysts that could not even be made in impure form can be readily made by self-assembly. Self-assembled catalyst compositions can also be extremely versatile. Catalyst composition properties can be tuned by adjusting the various components of the catalyst composition.
U.S. Pat. Nos. 5,378,567 and 5,451,555 to Tajima et al. relate to catalyst compositions for the homopolymerization or copolymerization of olefins. The catalyst compositions comprise a first compound of the formula Me.sup.1 (OR.sup.1).sub.p R.sup.2.sub.q X.sup.1.sub.4-p-q, wherein Me.sup.1 is Ti, Zr, or Hf, a second compound of the formula Me.sup.2 (OR.sup.3).sub.m R.sup.4.sub.n X.sup.2.sub.z-m-n, wherein Me.sup.2 is a Group I-III metal, and a third compound that is an organocyclic compound having two or more conjugated double bonds. A variety of organocyclic compounds are described in these patents, none of which are fulvenes.
Similarly, U.S. Pat. No. 5,331,071 to Kataoka et al. describes a process for the polymerization of olefinic hydrocarbons carried out in the presence of a catalyst component derived from reacting a compound of the formula Me.sup.1 R.sup.1.sub.n X.sup.1.sub.4-n, wherein Me.sup.1 is Ti, Zr, or Hf, a compound of the formula Me.sup.2 R.sup.2.sub.m X.sup.2.sub.z-m, wherein Me.sup.2 is a Group I-III metal, an organocyclic compound having two or more conjugated double bonds, and an inert carrier, along with a modified organoaluminum compound having Al--O--Al bonds. Again, a variety of organocyclic compounds are described, none of which are fulvenes.
U.S. Pat. No. 5,158,920 to Razavi discloses a process for the preparation of a bridged metallocene catalyst. The bridged cyclopentadienyl ligand of the catalyst is made by reacting a cyclopentadiene with substituted fulvene. The ligand is isolated and then contacted with a transition metal halide or hydrocarbon compound to form the bridged metallocene catalyst. Cocatalyst is subsequently added.
Derwent Abstract 96-088466/10 for DE 4434640 relates to the in situ production of a bridged metallocene catalyst by reacting a cyclopentadiene with a base, a bridging reagent, and a metal compound. The resulting stereorigid catalyst may be used for the polymerization of olefins.
Applicant has now discovered a self-assembled catalyst composition that may be easily and cost effectively made. The catalyst composition comprises the reaction product of a fulvene, a complex of an atom selected from Groups 3-14 and the Lanthanides, and an activating cocatalyst. The catalyst composition may contain a solvent as well, and is preferably used in unsupported, liquid form. Isolation of the catalyst composition or intermediates thereto is not required. Combinations of different fulvenes, complexes of an atom selected from Groups 3-14 and the Lanthanides, and activating cocatalysts can lead to versatile catalyst compositions that can be altered on-stream to match product and process requirements. Conditions used during catalyst composition formation such as temperature and concentrations of the reactants also can be used to control the properties of the resulting catalyst composition and polymer product.